The present invention relates generally to the communication of real time media, such as media data formatted pursuant to RTP (real-time transmission protocol), such as H.323, in a mobile, packet radio communication system. More particularly, the present invention relates to apparatus, and an associated method, by which to update a location register with an updated position of a mobile station operable in the communication system. Operation of an embodiment of the present invention provides a manner by which to maintain an accurate registry of position information of mobile stations operable to communicate RTP data in the mobile, packet radio communication system.
Advancements in communication technologies have permitted the introduction of, and popularization of, new types of, and improvements in existing, communication systems. Increasingly large amounts of data are permitted to be communicated at increasing throughput rates through the use of such new, or improved, communication systems. As a result of such improvements, new types of communications, requiring high data throughput rates, are possible. Digital communication techniques, for instance, are increasingly utilized in communication systems to efficiently communicate digital data, and the use of such techniques has facilitated the increase data throughput rates.
When digital communication techniques are used, information which is to be communicated is digitized. In one technique, the digitized information is formatted into packets, or frames, and, once formatted, the data is communicated upon a communication channel, thereby to be transmitted to a destination. Individual ones, or groups, of the packets or frames of data can be communicated at discrete intervals, and once communicated concatenated together to recreate the informational content contained therein.
Because data formatted in this manner can be communicated at the discrete intervals, a communication channel need not be dedicated solely for the communication of data generated by one sending station to one receiving station, as conventionally required in circuit-switched communications. Instead, a single channel can be shared amongst a plurality of different sending and receiving station-pairs. Because a single channel can be utilized to effectuate communications by the plurality of pairs of communication stations, improved communication capacity is possible.
Also through the use of digital communication techniques, any of a large number of different types of data can be communicated. And, more than one type of data can be communicated in a multi-media application. Different types of data exhibit different communication requirements however. For instance, voice data must be communicated in real time. That is to say, voice data must be communicated without significant delay and must be communicated in a manner which permits its reconstruction at a receiving station in a manner which introduces minimal time distortion. Otherwise, the voice data shall appear to be noticeably distorted.
Internet telephony is exemplary of communications which can be effectuated utilizing digital communication techniques. With the popularization of the Internet and communication thereon, standardized protocols have been set forth by which to communicate information in a form amenable to its transmission by way of the Internet. An example protocol is H.323. H.323 is a widely used ITU standard which uses RTP (real-time transmission protocol).
According to the H.323 protocol, when data is to be transmitted by a sending station, logical channels upon which to transmit the data are assigned. The data channels are allocated responsive to requests made by the sending station. Separate logical channels are requested for separate types of data. For instance, a first logical channel is requested upon which to transmit voice data, and allocation of a second logical channel is requested for transmission of non-voice data. A subset of the H.323 protocol, referred to as the H.245 protocol, defines the manner in which the channels are requested. Data is thereafter transmitted upon the logical channels. In conventional manner, individual packets, or frames, include header information, such as IP, UDP, and RTP information, to identify to where the packet is to be directed and to provide a time stamp with the packet. The informational content, referred to as the payload, is appended to the header information.
The H.323 protocol was intended originally for wireline communications, such as between communication stations, connected by wireline connections including those of the Internet. But, advancements in communication technologies have also permitted the widespread usage of radio communication systems. A cellular communication system is exemplary of a wireless communication system which has achieved wide levels of popularity and usage. Telephonic communication by way of a cellular communication system mimics communication by way of a conventional, wireline, telephonic system. However, difficulties arise when packet or frame-formatted data, such as that formatted pursuant to the H.323, or other RTP, protocol is communicated by way of a cellular communication system.
For instance, standards related to the H.323 protocol do not provide manners for implementing mobility for mobile stations operable in an H.323-based communication system. Maintenance of a location register with updated positional information related to the position of mobile stations is required in order to efficiently route data frames between sending and receiving stations operable pursuant to a communication session in the H.323-based system.
A manner by which to provide for updating of a location register in an H.323-based, or other RTP-type, radio communication system would therefore be advantageous.
It is in light of this background information related to radio communications that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides apparatus, and an associated method, for updating a location register of an H.323-based, or other RTP-based, radio communication system.
In operation of an embodiment of the present invention, a location register is accessible by a gatekeeper defined in the network of the RTP-based system. When a mobile station operable in the system crosses a boundary separating location areas, an indication of such crossing is provided to the gatekeeper. The indication is provided to the gatekeeper pursuant to a request to update the contents of the location register with updated positioning information pertaining to the position of the mobile station, If the request is granted, the updated position of the mobile station is registered at the location register, and the prior-registered position of the mobile station is removed from the location register. Requests to update the registered position of the mobile station are also made upon powering-up of the mobile station and at timed intervals, timed, for instance, by the mobile station.
In one implementation, an embodiment of the present invention is operable in an H.323 based system in which mobile stations are operable to communicate H.323-formatted data, such as pursuant to an Internet telephony application. The packet network of the H.323-based system includes radio access gateways (RAGWs). Each RAGW is formed of a base transceiver station (BTS) and a gateway part extending to an H.323 system. Because of the mobility provided to the mobile station, the mobile station might travel such that hand-over of communications are effectuated from one RAGW to another RAGW. And, the mobile terminal might travel to be repositioned when in an inactive state, also to be associated with another RAGW. If the first radio gateway, referred to as the source radio gateway, is part of a different location area (LA) than that with which the second radio gateway, referred to as the target gateway, the new position of the mobile station is updated, through operation of an embodiment of the present invention at a location register. Registration of the updated position of the mobile station is performed by an additive registration process.
In one aspect of the present invention, a gatekeeper is associated with the H.323 network. A mobile station initiates the location updating procedure by generating a location update request. The request is generated, for instance, when the mobile station is repositioned from one location area to another location area. And, the request is also generated during initial powering-up of the mobile station as well as at timed intervals. The request is transmitted upon a ratio link formed between the mobile station and a radio gateway. The receiving radio gateway, in turn, generates a RAS-protocol (registration, admissions, status-protocol) message which is routed through the H.323 network to the gatekeeper. A determination is made at the gatekeeper whether to update the location register. If a determination is made that the location register should be updated, the register is updated with the updated position of the mobile station, and a prior-stored position of the mobile station is removed from the location register. Another RAS-protocol message is returned by the gatekeeper to the radio gateway to confirm the updating of the location register. And, in turn, the radio gateway transmits a location update accept message back to the mobile station.
The mobile station might also be repositioned at a target radio gateway which is associated with a gatekeeper other than the gatekeeper with which the source radio gateway is associated. Again, the mobile station generates a location update request which is transmitted over a radio link to the target radio gateway. And, the target radio gateway generates an RAS-protocol message which is routed through the H.323 network to the gatekeeper associated with the target radio gateway. A determination is made at the gatekeeper whether to update the location register. If a determination is made to update the location register, the updated position of the mobile station is stored there at and a confirmation message, again an RAS-protocol message, is returned to the target radio gateway. Also, because the prior-stored position of the mobile station is stored at a gatekeeper other than the gatekeeper at which the updated position is stored, the gatekeeper associated with the prior-stored position is informed of the new registration at allocation register associated with the second gatekeeper.
Through operation of an embodiment of the present invention, therefore, a manner is provided by which to provide for mobility in an H.323-based, or other RTP-based, communication system. A manner is provided by which to update a location register with an updated position of the mobile station, such as when the mobile station travels between location areas defined in the communication system.
In these and other aspects, therefore, apparatus, and an associated method, is provided for updating a location register with an updated position of a mobile station operable in a packet radio communication system. The packet radio communication system defines a first location area formed of a first set of cells and at least a second location area formed of at least a second set of cells. The first and at least second location areas are separated by a location boundary. A determination is made of when the updated position of the mobile station should be updated at the location register. A request to update the location register with the updated position of the mobile terminal is generated when a determination is made that the location register should be updated with the updated position. If the request to update the location register is accepted, the location register is updated with the updated position of the mobile station. And, the updating of the location register with the updated position is thereafter confirmed.
A more complete appreciation of the present invention and the scope thereof can be obtained from the accompanying drawings which are briefly summarized below, the following detailed description of the presently-preferred embodiments of the invention, and the appended claims.